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The Effect of Crystal Mismatch on the Thermoelectric Performance Enhancement of Nano Cu2Se
Istanbul Univ Cerrahpasa, Dept Elect Elect Engn, Istanbul, Turkey..
Istanbul Univ Cerrahpasa, Dept Elect Elect Engn, Istanbul, Turkey..
KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.ORCID iD: 0000-0002-5672-5727
KTH, School of Engineering Sciences (SCI), Applied Physics.ORCID iD: 0000-0001-5678-5298
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2021 (English)In: FRONTIERS IN MATERIALS, ISSN 2296-8016, Vol. 7, article id 581138Article in journal (Refereed) Published
Abstract [en]

In the past decades, Cu2-x Se compounds have attracted great attention due to the inclusion of non-toxic and abundant elements, besides having a promising thermoelectric (TE) performance. In this work, we investigated the effect of a crystal mismatch of a nanoinclusion phase on the TE properties of Cu2-x Se. Nano-Cu2Se was synthesized using microwave assisted thermolysis, while the p-type skutterudite, Fe3.25Co0.75Sb12 (FeCoSb), compound was synthesized using a chemical alloying route. Nano-Cu2Se, and (nano-Cu2Se)(1-x )(nano-FeCoSb)( x ) composites, where x = 0.05 and 0.1, were prepared via mechanical alloying followed by Spark Plasma Sintering process. Structural properties were evaluated by PXRD and SEM analysis, while the high temperature transport properties were examined via electrical conductivity, Seebeck coefficient, and thermal conductivity measurements in the temperature range of 300-800 K. Powder X-ray diffraction (PXRD) confirmed a single phase of nano Cu2Se, while the samples with FeCoSb inclusion consist of two phases as Cu2Se and CoSb3. SEM micrographs of all samples show that Cu2Se has randomly oriented grains with different sizes. Cu2Se samples with a FeCoSb inclusion show a rather different structure. In these samples, a rod-shaped FeCoSb phase, with a size varying between 20 and 100 nm, showed an inhomogeneous distribution in the structure and stacked between the Cu2Se layers. Transport data indicate that crystal mismatch between Cu2Se and FeCoSb has a strong effect on the TE transport properties. Electrical conductivity decreases but Seebeck coefficient enhances with nano FeCoSb inclusion. Total thermal conductivity was suppressed by 30% and ZT value enhanced by 15% with 5% nano FeCoSb inclusion at 750 K, likely due to a decrease in the electronic contribution of the thermal conductivity. Structural and transport data show that small amount of nanoinclusion of FeCoSb has a beneficial effect on the TE performance of nano Cu2Se at temperatures below 800 K.

Place, publisher, year, edition, pages
Frontiers Media SA , 2021. Vol. 7, article id 581138
Keywords [en]
thermoelectric effect, microwave assisted thermolysis, nano Cu2Se, nano Fe325Co075Sb12, crystal mismatch, thermal conductivity
National Category
Chemical Sciences
Identifiers
URN: urn:nbn:se:kth:diva-291053DOI: 10.3389/fmats.2020.581138ISI: 000612813700001Scopus ID: 2-s2.0-85100266893OAI: oai:DiVA.org:kth-291053DiVA, id: diva2:1532531
Note

QC 20210302

Available from: 2021-03-02 Created: 2021-03-02 Last updated: 2022-06-25Bibliographically approved
In thesis
1. Design, Synthesis and Characterization of Nanostructured Thermoelectric Materials
Open this publication in new window or tab >>Design, Synthesis and Characterization of Nanostructured Thermoelectric Materials
2021 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The demand for energy is rapidly increasing, triggering more carbon emission and global warming. Alternative green energy sources are essential to secure the future generation from the effect of pollution and global warming. During the last few decades, thermoelectric (TE) materials gained interest, due to their capability of directly interconverting between heat and power, which can be used to convert waste heat to electricity.  One of the strategic TE adaptation approaches is to develop high efficiency TE materials from earth-abundant and non-toxic components. Not only the TE materials’ composition, but also the synthesis method, has to be environment friendly in order to create a green transition, with minimum adverse environmental impacts. Bottom-up microwave (MW) assisted synthesis routes, using water and polyalcohol as green solvents were demonstrated feasible to generate binary and ternary compositions of Bi2-xSbxTe3, which were effective in room temperature. A more earth abundant and environment friendly material composition, copper selenide (Cu2-XSe), effective at intermediate temperature regime (200-600 °C), was synthesized by MW-assisted thermolysis. The synthesized materials were characterized in terms of structure, microstructure, surface chemistry and TE transport properties, and showed significant improvement of TE performance compared to materials synthesized using conventional methods - mainly attributed to the preservation of nanostructure. Significant results have been achieved with improved material characteristics, while the time and the energy investment were substantially reduced. The developed processes with reduced time and carbon footprint offer excellent sustainable synthesis routes for large-scale synthesis of high-performance nanostructured TE materials as strategic energy materials. 

Abstract [sv]

Efterfrågan på energi ökar snabbt, vilket leder till mer koldioxidutsläpp och global uppvärmning. Alternativa gröna energikällor är nödvändigt för att skydda kommande generationer från effekterna av miljöföroreningar och global uppvärmning. Under de senaste decennierna har intresset för termoelektriska (TE) material ökat på grund av deras förmåga att direkt omvandla spillvärme till elektricitet. En av strategierna för TE-anpassning är att utveckla effektiva TE-material från i jordskorpan vanligt förekommande och ogiftig föreningar. Inte bara TE-materialens sammansättning, utan också hur de syntetiseras, bör vara miljövänligt för att skapa en grön övergång med minimal negativ miljöpåverkan. Grön mikrovågsassisterad botten upp syntes med vatten och sockeralkohol som lösningsmedel visades vara en möjlig metod för att generera binära och ternära föreningar av Bi2-xSbxTe3, vilka är effektiva vid rumstemperatur. Den i jordskorpan vanligt förekommande och miljövänliga kemiska föreningen kopparselenid (Cu2-XSe), vilken är effektivt vid mellantemperaturer (200-600°C), har syntetiseras genom MW-assisterad termolys. De syntetiserade materialen karakteriserades av deras struktur, mikrostruktur, ytkemi och termoelektriska transportegenskaper och visade betydande förbättringar av TE-prestanda jämfört med material syntetiserade med konventionella metoder, vilket primärt kan tillskrivas bevarandet av nanostrukturer. Betydande resultat har uppnåtts med överlägsna materialegenskaper, samtidigt som tid och energiåtgång reducerats avsevärt. Den utvecklade processen, med minskad tidsåtgång och koldioxidavtryck, erbjuder hållbara syntesvägar för storskalig syntes av effektiva TE-material med nanostrukturer för strategiska energimaterial.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2021. p. 75
Series
TRITA-SCI-FOU ; 2021:36
Keywords
Materials chemistry
National Category
Materials Chemistry
Research subject
Physics, Material and Nano Physics; Physics
Identifiers
urn:nbn:se:kth:diva-302383 (URN)978-91-8040-000-8 (ISBN)
Public defence
2021-10-15, BioX Library https://kth-se.zoom.us/j/63386528297, Albanova Universitetscentrum, Roslagstullsbacken 21, Stockholm och via zoom, Stockholm, 10:00 (English)
Opponent
Supervisors
Funder
Swedish Energy AgencyEuropean Commission
Available from: 2021-09-22 Created: 2021-09-21 Last updated: 2022-06-25Bibliographically approved

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